(1) Field of the Invention
The invention relates to a key control system and method, and especially relates to a key control system and method adapted to be used in the function of on-screen display (OSD) in a display apparatus.
(2) Description of the Related Art
Generally, screen usually has the function of on-screen display (OSD) which displays adjustment items on the screen, like brightness, contrast and color for users to adjust values of these items.
Referring to FIG. 1, a conventional on-screen display frame 100 includes a main menu 120 and a plurality of sub-menus 140. The main menu 120 includes a plurality of main items 122, and each of the main items 122 corresponds to one of the sub-menus 140, such as the sub-menu 140 corresponding to a brightness item 122 in the main menu 120 in FIG. 1. The sub-menu 140 includes a plurality of adjustment items 142. Each of the adjustment items 142 includes an icon 141 and a numerical adjusting area 143.
Referring to FIG. 2, a control keyboard 200 of the on-screen display frame 100 includes a power key 201, a menu key 202, an input key 203, an up key 204, a down key 205, a left key 206 and a right key 207. The power key 201 is capable of turning on a power supply of the screen. The menu key 202 is capable of opening the on-screen display frame 100. The up key 204 and the down key 205 are capable of moving a selecting box 102 or 104 upwards and downwards, in order to select the main item 122 of the main menu 120 or the adjustment item 142 of the sub-menu 140. When the selecting box 102 stops at the brightness item 122, users may press the input key 203 to enter the sub-menu 140 corresponding to the brightness item 122. The left key 206 and the right key 207 are used to adjust the value of the adjustment item 142 on the sub-menu 140.
However, each key on the conventional keyboard 200 only corresponds to one function, such as the power key 201 only for turning on or off the power supply of the display apparatus, thus at least seven keys are necessary to handle the on-screen display frame 100. Due to too many keys, the keyboard 200 has a large size and high cost, and thus makes the keyboard 200 unsuitable in a micro display apparatus such as handheld projector.